Field of the Invention
The present invention relates to a semiconductor device and method for forming the same, and in particular it relates to a fast recovery diode and method for forming the same.
Description of the Related Art
In fast recovery diodes, the majority of carriers of the current pass through the channel region under forward voltage conditions, and reverse recovery time (tRR), which is the time for turning the diode off and taking the minority carriers completely out, is reduced while maintaining soft-recovery properties under reverse voltage conditions since the amount of the reverse recovery electric charges is small. However, the higher the voltage that the fast recovery diodes endure, the longer the reverse recovery time (tRR) that the fast recovery diodes take.
In addition, when metal lines are formed across the fast recovery diodes, the early take off issue and leakage current will occur in the device. Generally, multiple metal layers are formed to make the metal layers away from the device to control these phenomena. However, the manufacturing cost is high for forming multiple metal layers.
Thus, a novel fast recovery diode with large forward current, short reverse recovery time, large reverse recovery softness factor and high-voltage endurance is desirable.